Flachi, Antonino

写真a

Affiliation

Faculty of Business and Commerce ( Hiyoshi )

Position

Professor
Scopus Paper Info  
Paper Count: 78 Citation Count: 1339 h-index: 22

Click to view the Scopus page. The data was downloaded from Scopus API in March 15, 2026, via http://api.elsevier.com and http://www.scopus.com .

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Papers 【 Display / hide 】

  • Remarks on the large-$N$ ${\mathbb C}P^{N-1}$ model

    Antonino Flachi

     2019.12

    　View Summary

    In this paper we consider the ${\mathbb C}P^{N-1}$ model confined to an
    interval of finite size at finite temperature and chemical potential. We
    compute, in the large-$N$ approximation, the one-loop effective action of the
    order parameter associated with the effective mass of the quantum fluctuations.
    To discuss some generic features of the ground state of the model, we work out
    a mixed-gradient expansion and obtain an expression for the thermodynamic
    potential density as a functional of the order parameter, generalizing previous
    calculations to arbitrarily large order and to the case of small finite
    density. The technique used here relies on analytic regularization and provides
    an efficient scheme to extract the coefficients of the expansion. These
    coefficients are then used to deduce some generic properties of the ground
    state as a function of external conditions. For vanishing chemical potential
    and intervals of any size, we show that inhomogeneous phases are not
    energetically favored, but we find evidence that they may become energetically
    favored for large enough values of the chemical potential. We also show that
    there can be no transition to a massless phase for any value of the external
    conditions and clarify a seemingly important point regarding the regularization
    of the effective action connected to the appearance of logarithmic divergences
    and to the Mermin-Wagner-Hoenberg-Coleman theorem.

  • Casimir force for the CP<sup>N−1</sup> model

    Flachi A., Nitta M., Takada S., Yoshii R.

    Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics (Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics)  798 2019.11

    ISSN  03702693

    　View Summary

    © 2019 In this work, we derive exact self-consistent solutions to the gap equations of the CPN−1 model on a finite interval with Dirichlet boundary conditions in the large-N approximation. The solution reproduces the confining phase in the infinite system by taking the appropriate limit. We compute the vacuum energy and the Casimir force and observe that the sign of the force is always attractive.

  • Ground state modulations in the CPN-1 model

    Flachi A., Fucci G., Nitta M., Takada S., Yoshii R.

    Physical Review D (Physical Review D)  100 ( 8 )  2019.10

    ISSN  24700010

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    © 2019 authors. Published by the American Physical Society. In this work we examine a system consisting of a confined one-dimensional arrangement of atoms that we describe by using the 2-dimensional CPN-1 model, restricted to an interval and at finite temperature. We develop a method to obtain the bulk and boundary parts of the one-loop effective action as a function of the effective mass of the fluctuations. The formalism has the advantage of allowing for a systematic analysis of a large class of boundary conditions and to model the (adiabatic) response of the ground state to changes in the boundary conditions. In the case of periodic boundary conditions, we find that inhomogeneous phases are disfavored for intervals of large size. Away from periodic boundary conditions, our numerical results show that the ground state has a generic crystal-like structure that can be modulated by variations of the boundary conditions. The results presented here could be relevant for experimental implementations of nonlinear sigma models and could be tested by lattice numerical simulations.

  • Cosmic strings, deformed lattices and spontaneous symmetry breaking

    A Flachi, V Vitagliano

    Journal of Physics: Conference Series 1275 (1), 012030 (Journal of Physics: Conference Series)  1275 ( 1 )  2019.09

    ISSN  17426588

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    © Published under licence by IOP Publishing Ltd. External conditions have a dramatic impact on the way dynamical symmetry breaking occurs. In a curved background, the natural expectation is that curvature works toward the restoration of the internal symmetry. We show instead that, for topological defects, the competing action of the locally induced curvature and boundary conditions generated by the non-trivial topology allows configurations where symmetries can be spontaneously broken close to the core. Inspired by the effect of geometrical deformations on 2D lattices, we then propose a novel mechanism to induce a superconducting phase by triggering condensation along cosmic strings.

  • Symmetry breaking and lattice kirigami: Finite temperature effects

    A Flachi, V Vitagliano

    Physical Review D 99 (12), 125010 (Physical Review D)  99 ( 12 )  2019.06

    ISSN  24700010

    　View Summary

    © 2019 authors. Published by the American Physical Society. Recent work has analyzed how deformations due to the insertion of a defect in a flat hexagonal lattice affect the ground state structure of an interacting fermion field theory. Such modifications result in an increase of the order parameter in the vicinity of the defect and can be explained by a kirigami effect, that is the combined effect of the curvature, locally introduced by the deformation in the lattice tessellation, and of a synthetic gauge field induced by the boundary conditions along the cut, performed to introduce the defect. In this work, we extend the formalism and previous results to include finite temperature effects.

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Papers, etc., Registered in KOARA 【 Display / hide 】

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Research Projects of Competitive Funds, etc. 【 Display / hide 】

  • Phase nucleation in curved space

    2021.04
    -
    2025.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

  • Quantum vacuum effects, symmetry breaking and gravity

    2018.04
    -
    2021.03

    MEXT,JSPS, Grant-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Principal investigator

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Courses Taught 【 Display / hide 】

  • SCIENCE AND THE ENVIRONMENT2

    2025

  • SCIENCE AND THE ENVIRONMENT1

    2025

  • SCIENCE AND COOKING2

    2025

  • SCIENCE AND COOKING1

    2025

  • REVIEW OF MODERN SCIENCE

    2025

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